Biology Past Paper

PP-DSE BIO

香港考試及評核局保留版權 Hong Kong Examinations and Assessment Authority All Rights Reserved 2012

Not to be taken away before the end of the examination session

PAPER 1A

HONG KONG EXAMINATIONS AND ASSESSMENT AUTHORITY

HONG KONG DIPLOMA OF SECONDARY EDUCATION EXAMINATION

PRACTICE PAPER

BIOLOGY PAPER 1

(2 hours 30 minutes)

This paper must be answered in English

GENERAL INSTRUCTIONS

1. There are TWO sections, A and B, in this Paper. You are advised to finish Section A in about

35 minutes. 2. Section A consists of multiple-choice questions in this question paper. Section B contains

conventional questions printed separately in Question-Answer Book B.

3. Answers to Section A should be marked on the Multiple-choice Answer Sheet while answers to Section B should be written in the spaces provided in Question-Answer Book B. The Answer Sheet for Section A and the Question-Answer Book for Section B will be collected separately at the end of the examination.

INSTRUCTIONS FOR SECTION A (MULTIPLE-CHOICE QUESTIONS) 1. Read carefully the instructions on the Answer Sheet. After the announcement of the start of

the examination, you should first stick a barcode label and insert the information required in the spaces provided. No extra time will be given for sticking on the barcode label after the ‘Time is up’ announcement.

2. When told to open this book, you should check that all the questions are there. Look for the

words ‘END OF SECTION A’ after the last question. 3. All questions carry equal marks. 4. ANSWER ALL QUESTIONS. You are advised to use an HB pencil to mark all the answers

on the Answer Sheet, so that wrong marks can be completely erased with a clean rubber. You must mark the answers clearly; otherwise you will lose marks if the answers cannot be captured.

5. You should mark only ONE answer for each question. If you mark more than one answer,

you will receive NO MARKS for that question. 6. No marks will be deducted for wrong answers.

PP-DSE-BIO 1A–1 1

There are 36 questions in this section. The diagrams in this section are NOT necessarily drawn to scale. 1. In a DNA molecule of yeast, 30% of the nitrogenous bases are guanine (G). What is the ratio of

cytosine (C) to thymine (T) in this DNA molecule? A. 1:1 B. 2:1 C. 3:2 D. 3:7

2. The graph below shows the change in the amount of DNA in a cell which is undergoing cell division:

4

2

Which of the following statements correctly describes the event that is taking place in the respective time period?

A. During t1, the nuclear membrane disappears. B. During t2, the homologous chromosomes pair up. C. During t3, the homologous chromosomes separate. D. During t4, the synthesis of cell organelles takes place.

3. The following diagram shows an animal cell with some of its organelles:

Which of the labelled structures are particularly abundant in an enzyme-secreting cell?

A. P and Q only B. P and R only C. Q and R only D. P, Q and R

0Am

ount

N

A in

the

cell

t3 t4t1 t2

of D

(arb

itrar

y un

it)

Time

R

P Q

PP-DSE-BIO 1A–2 2

4. In an experiment to investigate the effect of temperature on the activity of a digestive enzyme X, the time taken for the digestion of a fixed amount of substrate by this enzyme was recorded. Which of the following graphs shows the most likely results of the experiment?

A.

B.

Rel

ativ

e ra

te o

f en

zym

atic

rea

ctio

n (m

in–1

)

Rel

ativ

e ra

te o

f en

zym

atic

rea

ctio

n (m

in–1

)

Temperature (oC) Temperature (oC)

C.

D.

Rel

ativ

e ra

te o

f en

zym

atic

rea

ctio

n (m

in–1

)

Rel

ativ

e ra

te o

f en

zym

atic

rea

c tio

n (m

in–1

)

Temperature (oC)

Temperature (oC)

5. The table below shows the ratios of initial mass to final mass of three fresh potato cylinders which have been immersed in sucrose solutions of three different concentrations for 30 minutes:

Solution P Solution Q Solution R Ratio of initial mass to final mass 0.9 1.4 1.2

Which of the following can be deduced from the results?

(1) The water potential of the potato cylinders is higher than that of solution P.

(2) There is a net movement of water from the potato cylinders to solution Q.

(3) Solution Q has a higher sucrose concentration than solution R.

A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only

6. In photosynthesis, photochemical reactions are essential for the carbon fixation that follows. This is because in photochemical reactions,

(1) oxygen is liberated.

(2) NADPH is generated.

(3) the carbon dioxide acceptor is regenerated.

A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only

PP-DSE-BIO 1A–3 3 Go on to the next page

7. Which of the following correctly lists the substances formed in the Krebs cycle?

A. water and NADH

B. water and carbon dioxide

C. carbon dioxide and NADH

D. water, carbon dioxide and NADH

8. The graph below shows the rate of photosynthesis of a plant at different temperatures and carbon dioxide concentrations when light intensity increases:

Rat

e of

pho

tosy

nthe

sis

(arb

itrar

y un

it) 40

30

20

10

0

15oC and 0.5% carbon dioxide



0 5 10 15 20 25 30

Light intensity (arbitrary unit)

Which of the following descriptions about the rate of photosynthesis of this plant can be deduced from the graph?

A. Below 3 units of light intensity, light intensity is the factor limiting this plant’s photosynthetic rate.

B. At 25 units of light intensity and 0.02% carbon dioxide, temperature is the factor limiting this plant’s photosynthetic rate.

C. At 25 units of light intensity, 15oC and 0.5% carbon dioxide, carbon dioxide concentration is the factor limiting this plant’s photosynthetic rate.

D. At 25 units of light intensity, 15oC and 0.5% carbon dioxide, this plant’s photosynthetic rate doubles when the temperature is doubled.

PP-DSE-BIO 1A–4 4

Directions: Questions 9 and 10 refer to the following table, which shows six codons and the corresponding amino acids translated from these codons:

mRNA codon AAG CUA CCU GUA GAU CAU

amino acid lysine leucine proline valine aspartic acid histidine

9. The sequence of amino acids in a certain part of a polypeptide is shown below: —lysine—proline—histidine—aspartic acid—

Which of the following is the correct sequence of the nucleotides on the non-template DNA (coding DNA) for this part of the polypeptide?

A. AAGCCTCATGAT

B. TTCGGAGTACTA

C. AAGCCUCAUGAU

D. UUCGGAGUACUA

10. The following shows the nucleotide sequences of two mRNA molecules, the first one being transcribed from a normal allele and the second one from the mutated allele: mRNA transcribed from the normal allele: CCUGAUCCUCUACCUCAU

mRNA transcribed from the mutated allele: CCUGAUCCUGUACCUCAU

Which of the following amino acids is absent in the polypeptide translated from the mutated allele?

A. histidine

B. aspartic acid

C. valine

D. leucine

11. A couple has two children. The son is of blood group B and the daughter is of blood group A. Which of the following is not a possible combination of genotypes of this couple?

(Note: The alleles responsible for the production of antigen A, antigen B and not producing antigen A or B are represented by IA, IB and i respectively.)

A. IAi and IBi

B. IAIA and IBi

C. IAIB and IAIB

D. IAIB and IBi

12. Which of the following processes may increase the variation of a particular character within a population?

A. the mutation of genes

B. the separation of homologous chromosomes during meiosis

C. the independent assortment of homologous chromosomes during meiosis

D. the random fertilisation of gametes


13. In guinea pigs, the genes for fur colour and hair length are located on different chromosomes. The alleles for black fur and long hair are recessive to the alleles for brown fur and short hair respectively. Guinea pigs which are heterozygous for both fur colour and hair length are allowed to breed. Of the 112 offspring produced, how many are expected to have black fur and short hair?

A. 21

B. 28

C. 56

D. 63

14. Mr. Chan and Mrs. Chan are the biological parents of four children. The DNA profiles of Mr. Chan and the four children are shown below:

Mr. Chan child 1 child 2 child 3 child 4

Which of the following is likely to be the DNA profile of Mrs. Chan?

A.

B.

C.

D.

15. Which of the following combinations shows the correct classification of the organism according to the

Three Domain System?

Organism Kingdom Domain

A. nitrifying bacteria Archaebacteria Bacteria

B. amoeba Animalia Eukarya

C. yeast Fungi Archaea

D. algae Protista Eukarya

16. Below are the scientific names of four species of shrimps:

(1) Leptochela japonicus

(2) Metapenaeus japonicus

(3) Metapenaeus joyneri

(4) Metapenaeopsis dura

Which two of the above species should have the closest phylogenetic relationship?

A. (1) and (2)

B. (1) and (4)

C. (2) and (3)

D. (3) and (4)

PP-DSE-BIO 1A–6 6

17. The following dichotomous key can be used to identify five species of amphibian:

1 (a) the skin is rough ----------------------------------------------------- 2

1

(b) the skin is smooth --------------------------------------------------- 3

2 (a) the dorsal side has coloured stripes ---------------------------- Species P

2

(b) the dorsal side does not have coloured stripes --------------

Species Q

3 (a) the toes have sticky pads ----------------------------------------- 4

3 (b)

the toes do not have sticky pads -------------------------------- Species R

4 (a) the limbs are spotted ----------------------------------------------- Species S

4 (b) the limbs are not spotted ------------------------------------------ Species T

Use the above key to identify the three amphibians in the following photographs.

Amphibian (1) Amphibian (2) Amphibian (3)

Amphibian (1) Amphibian (2) Amphibian (3)

A. species R species Q species S

B. species Q species S species R

C. species T species R species P

D. species T species Q species S

18. In an aquatic ecosystem, species X, Y and Z form a food chain. The following diagram shows the pyramid of biomass of this ecosystem:

Species Z

Species Y

Species X

With reference to the above pyramid of biomass, which of the following statements are correct?

(1) Species Z is the secondary consumer in this food chain.

(2) The body size of species X is larger than that of species Y.

(3) There is an energy loss when energy flows from species Y to species Z.

A. (1) and (2) only

B. (1) and (3) only

C. (2) and (3) only

D. (1), (2) and (3)


19. Three types of seaweeds, P, Q and R, were collected from the intertidal zone (the zone between the high tide mark and the low tide mark) of a rocky shore. The distribution of these seaweeds in the intertidal zone is related to their ability to withstand exposure to air. The graph below shows the changes in the fresh mass of these seaweeds when they are left to dry in the laboratory:

Fre

sh m

ass

Time

Q R

P

0

Which of the following shows the most likely distribution of these seaweeds from the lower shore to the upper shore?

A. P, Q, R

B. P, R, Q

C. Q, R, P

D. R, Q, P

20. In the table below, P and Q represent two types of relationships between different species of organisms. The effect of each type of relationship on the species concerned is represented by the following symbols:

+ = gaining benefits

─ = being harmed

Effect of the relationship on the species Type of relationship

between species Species 1 Species 2

P + +

+ Q ─

Which of the following combinations correctly shows the types of relationships represented by P and Q?

P Q

A. competition commensalism

B. mutualism competition

C. commensalism parasitism

D. mutualism predation

21. Which of the following is not a limitation of the use of fossil records as evidence for evolution?

A. Fossils are damaged and incomplete.

B. Some organisms may not form fossils.

C. Fossils are found in different sedimentary rock layers.

D. Fossils present in inaccessible areas are not available to us for study.

PP-DSE-BIO 1A–8 8

22. Which of the following are necessary for speciation?

(1) the competition within a species

(2) the existence of variation within a species

(3) different populations of a species being isolated for a long time

A. (1) and (2) only

B. (1) and (3) only

C. (2) and (3) only

D. (1), (2) and (3)

23. In constructing an evolutionary tree, it is assumed that the more similarities shared between two species, the closer is their phylogenetic relationship. The amino acid sequences of a certain protein in five species of organisms were analysed and compared. The following table shows the number of amino acid differences between the amino acid sequence of species P and that of each of the other four species:

Species Q R S T

The number of amino acid differences between the amino acid sequence of species P and that of the other species

31 16 36 1

Assuming that these five species of organisms arose from the same ancestral stock, which of the following diagrams best represents the evolutionary tree constructed using the above information?

A. P T R Q S

B. P T R Q S

ancestor ancestor

C. S Q R T P

D. S Q R T P

ancestor

ancestor

24. Which of the following descriptions about the regulation of the blood glucose level is correct?

A. The chemoreceptor in the liver detects changes in the blood glucose level.

B. The liver secretes more glucagon when the blood glucose level is low.

C. More glycogen is converted to glucose when more glucagon is secreted.

D. More glucose is taken up by cells when more glucagon is secreted.


25. The flow chart below shows the interaction between the two endocrine glands and the hormones they secrete:

Which of the following combinations correctly shows the regulation of hormone Y by a negative feedback mechanism?

(1)

(2)

Endocrine gland P

Endocrine gland Q

Hormone X

Hormone Y

secretion

secretion

(3)

(1) (2) (3)

A. inhibition stimulation inhibition

B. inhibition inhibition stimulation

C. stimulation stimulation inhibition

D. stimulation inhibition stimulation

26. Which of the following parts of the human skin are responsible for preventing us from microbial

infections?

(1) sebaceous gland

(2) epidermis

(3) hair

A. (1) and (2) only

B. (1) and (3) only

C. (2) and (3) only

D. (1), (2) and (3)

PP-DSE-BIO 1A–10 10

27. The diagram below shows a weight potometer used in an experiment. The leafy shoot was left in the laboratory for 3 hours. The change in the reading of the electronic balance and the change in the volume of water in the measuring cylinder were recorded. The experiment was then repeated under the same environmental conditions with the upper surface of all the leaves of the shoot smeared with vaseline. The results are shown in the following table:

leafy shoot

oil layer

measuring water

cylinder

electronic

balance

Treatment Change in the reading of the

balance (g)

Change in the volume of water in the measuring

cylinder (mL)

(I) Leaves not smeared with vaseline

p r

(II) Upper surface of all leaves smeared with vaseline

q s

Note:

1. p, q, r and s are numerical values

2. mass of 1 mL of water = 1 g

From the results of the experiment, we can calculate the amount of

A. water absorbed by the shoot in Treatment (I) from p – r.

B. water transpired by the shoot in Treatment (II) from r – s.

C. water retained by the shoot in Treatment (II) from s – q.

D. water transpired by the lower surface of the leaves of the shoot in 3 hours from p – q.

28. The photographs below show the appearances of a flower at different times of a day:

8:00 am 2:00 pm

With reference to the appearances of the flower at the times shown, which of the following can be concluded?

(1) The major support in the flower stalk is provided by the turgidity of the cells.

(2) The rate of water uptake of the flower is higher than its rate of transpiration at 8:00 am.

(3) The rate of water uptake of the flower is lower than its rate of transpiration at 2:00 pm.

A. (1) only

B. (2) only

C. (1) and (3) only

D. (2) and (3) only


29. The following photograph shows a section of a part of the human intestine:

X

Which of the following is/are the function(s) of X?

(1) to move the food along the intestine by peristalsis

(2) to secrete enzymes for fat digestion

(3) to absorb digested food

A. (1) only

B. (3) only

C. (1) and (2) only

D. (2) and (3) only

30. The following graph shows the change in the air pressure inside the lungs within a period of time:

Atmospheric pressure = 760 mm Hg

Which of the following correctly describes what happens at the specified time period?

A. During t1, air leaves the lungs.

B. During t2, the intercostal muscles contract.

Air

pre

ssur

e in

the

lung

s (m

m H

g)

t4t3t2 t1

760

Time

C. During t3, the diaphragm is pulled flat.

D. During t4, the rib cage is moved upwards and outwards.


31. The following photograph shows a dissected pig’s heart:

Pulmonary artery

P

R

Q

S

Which of the following descriptions of the labelled structures is correct?

A. Structure P contracts to deliver blood to various parts of the body except the lungs.

B. Structure Q receives blood from the pulmonary veins.

C. Structure R controls the opening and closing of the valve.

D. Structure S contracts to force the blood out of the heart through the pulmonary artery.

32. The photograph below shows the cross section of the umbilical cord of a foetus:

Blood vessel X

Blood vessel Y

Which of the following descriptions about blood vessels X and Y are correct?

(1) The blood pressure in blood vessel Y is lower than that in blood vessel X.

(2) There are valves along the length of blood vessel Y but not in blood vessel X.

(3) The blood in blood vessel Y has a lower oxygen content than that in blood vessel X.

A. (1) and (2) only

B. (1) and (3) only

C. (2) and (3) only

D. (1), (2) and (3)


33. The photograph below shows the cross section of a leaf:

1

2 3

4

There is a gas released by the leaf when it is placed in darkness. From which of the labelled cells is this gas released?

A. 1 and 2 only

B. 1 and 4 only

C. 2 and 3 only

D. 1, 3 and 4 only

34. The following shows a table listing the results of the food tests for a piece of food and a diagram of the human digestive system:

Food test Result

R S Q

P Albustix paper +

Benedict’s test +

Iodine test –

Grease spot test +

Key:

+ positive result

– negative result

In which of the labelled parts will this food be chemically digested?

A. P and S only

B. Q and R only

C. R and S only

D. Q, R and S only


Directions: Questions 35 and 36 refer to the following description of an experiment, which was carried out in the 1880s by a scientist, Christiaan Eijkman, for identifying the cause of the disease beriberi:

Group Experimental conditions Result after 5 weeks

I chickens with beriberi and healthy chickens kept together; fed with unpolished rice

chickens with beriberi recovered, others remained healthy

II healthy chickens injected with bacteria taken from chickens with beriberi; fed with unpolished rice

all chickens remained healthy

III healthy chickens; fed with polished rice

all chickens developed beriberi

IV healthy chickens; fed with unpolished rice

all chickens remained healthy

35. Which of the following can be concluded from this experiment?

(1) Beriberi is not caused by the bacteria taken from chickens with beriberi.

(2) Beriberi is most likely non-infectious.

(3) Eating unpolished rice can prevent beriberi in healthy chickens.

A. (1) and (2) only

B. (1) and (3) only

C. (2) and (3) only

D. (1), (2) and (3)

36. In light of the results of this experiment, Eijkman used prisoners for testing whether the same cause led to beriberi in humans. Which of the following should have been included in the experimental design so that he could make a valid conclusion?

(1) The test should have been performed on healthy prisoners.

(2) The controlled variables should have included the sex, age and body mass of the prisoners.

(3) The prisoners chosen for the test should have been randomly assigned to the experimental and control groups.

A. (1) and (2) only

B. (1) and (3) only

C. (2) and (3) only

D. (1), (2) and (3)

END OF SECTION A

Go on to Question-Answer Book B for questions on Section B



PP-DSE-BIO 1B–1 1

*A130E01B*

PP-DSE BIO

PAPER 1B



PRACTICE PAPER

BIOLOGY PAPER 1

SECTION B : Question-Answer Book B


INSTRUCTIONS FOR SECTION B

(1) After the announcement of the start of the examination,

you should first write your Candidate Number in the space provided on Page 1 and stick barcode labels in the spaces provided on Pages 1, 3, 5, 7 and 9.

(2) Refer to the general instructions on the cover of the

Question Paper for Section A. (3) Answer ALL questions. (4) Write your answers in the spaces provided in this

Question-Answer Book. Do not write in the margins. Answers written in the margins will not be marked.

(5) Supplementary answer sheets will be supplied on

request. Write your candidate number, mark the question number box and stick a barcode label on each sheet, and fasten them with string INSIDE this Question-Answer Book.

(6) Present your answers in paragraphs wherever

appropriate. (7) The diagrams in this section are NOT necessarily drawn

to scale. (8) No extra time will be given to candidates for sticking on

the barcode labels or filling in the question number boxes after the ‘Time is up’ announcement.

B

Please stick the barcode label here.

Candidate Number

PP-DSE-BIO 1B–2 2

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Answers written in the margins will not be marked.

SECTION B

Answer ALL questions. Put your answers in the spaces provided.

1. For each of the infectious diseases listed in Column 1, select one of the methods listed in Column 2 that helps to protect people from contracting the disease. Put the appropriate letter in the space provided.

(2 marks)

Column 1 Column 2

Cholera A. using serving chopsticks and spoons at meal times B. boiling water before drinking Dengue fever C. wrapping up rubbish properly before disposal D. wearing a face mask in crowded places E. getting rid of stagnant water

2. The following shows an electronmicrograph of a cell taken from a leaf:

ed.

(a) Name the type of cell shown in the electronmicrograph. (1 mark)

(b) Using the letters in the electronmicrograph, fill in the table below to show the structures in which

ATP is synthesised. State the process by which ATP is synthesised in each structure. (4 marks)

Structure Process of ATP synthesis

Q

S

P

T

R

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3. The electronmicrograph below shows two types of photoreceptors in the human eye:

Go on to the next page

(a)

A

B

Name the part of the human eye where the photoreceptors are found. (1 mark)

(b) A coloured object is perceived as being more colourful in bright light than in dim light. Explain

this with respect to the functioning of photoreceptors A and B. (4 marks)

PP-DSE-BIO 1B–3 3

PP-DSE-BIO 1B–4 4

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in th

4. When a slice of apple is exposed to air, it quickly turns brown. This is because the enzyme

diphenol oxidase catalyzes the oxidation of phenols in the apple to dark-coloured products. In an experiment, the effect of a chemical, PHBA, on the rate of this enzymatic reaction was investigated. The experiment was carried out at the same temperature and the same concentration of diphenol oxidase was used. The results are shown in the graph below:

(a) Deduce the relationship between PHBA and diphenol oxidase. (3 marks)

(b) Draw a curve in the above graph to show the effect of PHBA on the rate of enzymatic reaction if a

higher concentration of PHBA had been used. (1 mark) (c) Suggest one other factor that should be kept constant in this experiment. Explain how this factor

may affect the activity of the enzyme. (3 marks)

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ativ

e ra

te o

f en

zym

atic

rea

ctio

n (a

rbitr

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unit)

Concentration of phenol (arbitrary unit)

Key: diphenol oxidase alone diphenol oxidase + PHBA

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5. A sandy shore community has three species: a burrowing clam, a snail, and a crab.

sand

(a) To determine the relative abundance of these species, a student placed a quadrat on the shore and

collected all the individuals on the sediment surface inside the quadrat. After counting the number of individuals of each species collected from this quadrat, he determined their relative abundance. Give three reasons why the student’s sampling method may not reflect the actual relative abundance of these organisms. (3 marks)

(b)

The feeding relationship of these three species is shown below:

Suggest the effect on the population of crabs if a large number of clams are harvested by visitors

to the shore. Explain your answer. (2 marks)(Assume that the crabs have the same preference for snails and clams.)

Crabs

Snails Clams

PP-DSE-BIO 1B–5 5 Go on to the next page

PP-DSE-BIO 1B–6 6

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6. A test was carried out to investigate the effects of four antibiotics against a species of bacteria isolated

from a patient. The bacteria were inoculated on the surface of an agar plate. Four filter-paper discs (each with a diameter of 5 mm) soaked with different antibiotics A, B, C and D were placed on the surface of the agar. The agar plate was then incubated to allow the growth of the bacteria. If bacterial growth is inhibited by an antibiotic, a clear zone surrounding the filter-paper disc soaked with the antibiotic will be observed after 24 hours. The results of the test are shown below:

The following table shows the diameter of the clear zone measured in each of the filter-paper discs:

Antibiotic Diameter of the clear zone (mm) A 13 B 5 C 10 D 21

(a) Explain why the agar plate should be incubated at 37 oC. (1 mark)

(b) (i) Based on the results, arrange the four antibiotics in descending order of effectiveness at

inhibiting bacterial growth. (1 mark)

Incubate for 24 hours

Diameter of clear zone

A

B

D

C

Agar plate inoculated with bacteria Area with bacterial growth

Paper disc soaked with antibiotic

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(ii) Explain your reasoning in determining the order in (i). (3 marks)


(c) Antibiotic B has been commonly used. It was the most effective antibiotic against the same

bacteria a few years ago. Explain the result of antibiotic B in this test. (4 marks)

PP-DSE-BIO 1B–7 7

PP-DSE-BIO 1B–8 8

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7. Mr. Chan has been a smoker for more than 25 years. He has excessive rapid breathing and experiences

chest pain during vigorous exercise. When consulting the doctor, he was advised to undertake an imaging of his heart for diagnosis. The image taken is shown below:

ed.

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(a) (i) Identify artery X. (1 mark)

(ii) Based on the condition shown in the above image, explain why Mr. Chan may suffer from a

heart attack during vigorous exercise. (3 marks)

Narrowed artery X


PP-DSE-BIO 1B–9 9



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(b) The doctor advised Mr. Chan to quit smoking and to adopt a low-fat diet. With reference to

Mr. Chan’s health condition, give a reason for each piece of advice. (2 marks)

(i) Quitting smoking

(ii) Adopting a low-fat diet

PP-DSE-BIO 1B–10 10

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8. Graph 1 shows the change in the soil nitrogen content in an area over 200 years. At the beginning of

Stage 1, the area was without vegetation. Table 1 shows the relative abundance of three plant species found in this area at the different stages:

Soil

nitr

ogen

con

tent

(a

rbitr

ary

unit)

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Table 1

(a) With reference to Table 1, state the process that accounts for the change in the relative abundance of the plant species in this area. (1 mark)

(b) (i) The bacteria living symbiotically with plant species A and species B played an important

role in causing the increase in the soil nitrogen content in Stages 1 and 2.

(1) Name the symbiotic bacteria living in plant species A and B. (1 mark)

Relative abundance of the plant species at the end of each stage (%)

Plant species

Stage 1 Stage 2 Stage 3 A 95 10 5 B 5 85 20 C 0 5 65

Year Stage 1 Stage 2 Stage 3

Graph 1



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(2) Describe how the symbiotic bacteria and the two plant species caused the increase in

the soil nitrogen content in Stages 1 and 2. (3 marks)

(ii) Species C was absent in Stage 1 but became the dominant species in Stage 3. Explain the

change in its relative abundance from Stage 1 to Stage 3. (3 marks)



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9. A couple (A and B) does not have any family history of Down syndrome, but the female (B) has a family

history of colour blindness. The two daughters of this couple do not have colour blindness, but one of them (C) has Down syndrome. The son (E) has colour blindness. The pedigree of this family is shown in the following diagram:

Key: Male with normal colour vision

A B

Colour-blind male

Female with normal colour vision

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C D E F ?

(a) Normal people have 23 pairs of chromosomes in the cell nucleus, but people with Down syndrome have an extra chromosome in the 21st pair of chromosomes. Explain how this couple could give birth to a Down syndrome child (C). (2 marks)

(b) (i) In humans, colour blindness is a sex-linked trait. Based on the above pedigree, deduce the

genotype of the mother (B) with respect to colour vision. (Marks will not be awarded for genetic diagrams.) (5 marks)


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(ii) F is a carrier of the colour blindness allele. With the aid of a genetic diagram, find the

probability of E and F giving birth to a colour-blind daughter. (5 marks)

Genetic diagram:

Probability of E and F giving birth to a colour-blind daughter:


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10. (a) Photograph 1 shows two groups of wheat flowers and Photograph 2 shows an enlarged wheat

flower:

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Photograph 1 Photograph 2

Suggest the agent for pollination of the wheat. Support your answer with reference to an

observable feature in the above photographs. (2 marks)

(b) Explain the importance of soaking wheat grains in water for germination. (2 marks)


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(c) When wheat grains are sown on a piece of farmland which has been frequently sprayed with a

pesticide X, the germination rate is poor. Design an experiment to investigate whether pesticide X affects germination of the wheat grains. (4 marks)


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11. Digested food is absorbed into the epithelial cells of the villi. (a) With reference to the structure of the cell membrane as illustrated by the fluid mosaic model of

cell membrane, explain the following:

(i) Fatty acids (non-polar molecules) can diffuse across the cell membrane into the epithelial

cell. (2 marks)

(ii) Amino acids (polar molecules) can be taken up from the intestinal lumen into the epithelial

cell but cannot diffuse across the epithelial cell membrane back to the lumen. (3 marks)

(b) Name a mechanism for transporting glucose across the cell membrane. State a difference between

this mechanism and diffusion. (2 marks)



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For question 12, candidates are required to present their answers in essay form. 7 marks will be

allocated to biological knowledge, and 3 marks to logical presentation and clarity of expression.

12. Being able to respond to external stimuli is very important for the survival of organisms. Illustrate this

with reference to one tropic response in flowering plants. Contrast the nature and process of this type of response with that involved in reflex action in humans. (10 marks)

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END OF PAPER

Sources of materials used in this paper will be acknowledged in the Hong Kong Diploma of Secondary Education Examination Practice Papers published by the Hong Kong Examinations and Assessment Authority at a later stage.


Do not write on this page.

Answers written on this page will not be marked.

PP-DSE BIO


Not to be taken away before the end of the examination session

PAPER 2



PRACTICE PAPER

BIOLOGY PAPER 2

(1 hour)


INSTRUCTIONS

(1) There are FOUR sections, A, B, C and D in this Paper. Attempt ALL questions in any TWO sections.

(2) Write your answers in the Answer Book provided. Start each question (not part

of a question) on a new page. (3) Present your answers in paragraphs wherever appropriate. (4) Illustrate your answers with diagrams wherever appropriate. (5) The diagrams in this paper are NOT necessarily drawn to scale.

PP-DSE-BIO 2–1 1

SECTION A Human Physiology: Regulation and Control Answer ALL parts of the question. 1. (a) The following graph shows the plasma concentrations of progesterone, luteinising hormone and follicle

stimulating hormone of a woman over a period of time:

10 1000 8 800 6 600 4 400 2 200 0 0

Con

cent

ratio

n of

pro

gest

eron

e in

pla

sma

(ng

mL

–1)

Progesterone

0 7 14 21 28 35 42

Concentration of luteinising horm

one and follicle stim

ulating hormone in plasm

a (ng m

L–1)

Luteinising hormone

Follicle stimulating hormone

Beginning of menstruation Time (day)

(i) Name the process that took place in the ovary on day 14. (1 mark) (ii) Account for the change in the plasma concentration of progesterone from day 14 to day 42. (3 marks)

(iii) What would happen to the woman if the progesterone level dropped significantly on day 35?

(1 mark) (iv) With reference to the changes in the concentration of the hormones shown in the above graph,

explain why progesterone can be used as a drug for contraception. (3 marks)

PP-DSE-BIO 2–2 2

1. (b) The table below shows the data of some parameters of the cardiovascular and respiratory systems of a healthy untrained person at rest, during light exercise and during vigorous exercise:

At rest Light exercise Vigorous exercise

Heart rate (beats / min) 75 145 190

Stroke volume (dm3) 0.07 0.09 0.11

Breathing rate (breaths / min) 14 24 40

Tidal volume (dm3 ) 0.86 1.67 2.50

(i) Using the data provided, calculate the cardiac output (dm3 / min) and ventilation rate (dm3 / min) of this person when he is at rest, when he is doing light exercise and when he is doing vigorous exercise respectively. (2 marks)

(ii) State the changes in this person’s cardiac output and ventilation rate with the increasing level of

exercise. What is the importance of these changes? (4 marks)

(iii) Describe how the person’s sympathetic nerve brings about the change in the cardiac output during exercise. (2 marks)

(iv) Explain why the volume of urine produced by this person after vigorous exercise is less than usual.

(4 marks)

PP-DSE-BIO 2–3 3 Go on to the next page

SECTION B Applied Ecology

Answer ALL parts of the question. 2. (a) Many bird species living in Canada migrate southwards to the U.S.A. to spend the winter. The diagram

below shows the destinations of some of these bird species in the U.S.A. in the winters of 1966 and 2005:

aCanadaa

aU.S.A.a

Ring-necked duck

Rail Sparrow

Jay

Thrush

Nuthatch Siskin

N Finch

Key: Winter destination in 1966 Winter destination in 2005

Change in winter destination

. The average January temperatures in the U.S.A. from 1966 to 2005 are shown in the following graph:

4.4

1.6

–1.2

–4.0

–6.8

Ave

rage

Jan

uary

tem

pera

ture

i

n th

e U

.S.A

. (°C

)

1966 1970 1980 1990 2000 2005 Year

(i) Suggest one way which can be used to track the migration route of birds. (1 mark)

(ii) (1) State the general trend shown in the average January temperature in the U.S.A. from 1966 to 2005. (1 mark)

(2) Relate the change in the winter destination of bird species in the U.S.A. with the change

in average January temperature in the U.S.A. from 1996 to 2005. Suggest, from an ecological point of view, a reason for the change in the winter destination. (2 marks)

(3) Suggest two possible effects caused by the change in the winter destination of these

migratory bird species on native bird species. (2 marks) (4) It is believed that the trend in the average January temperature in the U.S.A. is due to

human activities. Explain how human activities may have caused this trend. (4 marks)

PP-DSE-BIO 2–4 4

2. (b) Forests provide humans with valuable resources. Proper forest management is needed when exploring new uses of forests to ensure sustainable forestry.

(i) The combustion of fossil fuel releases acidic gases which may cause acid rain. State and explain

two environmental impacts of acid rain. (4 marks)

(ii) Some scientists are exploring the use of forest woody biomass to replace the fossil fuel used in power plants. Trees are logged from two forests, A and B, for this research and other uses. The table below shows the distribution of the inorganic nutrients nitrogen and magnesium in these two forests:

Forest A Forest B

Nitrogen (%) Magnesium (%) Nitrogen (%) Magnesium (%)Biomass above forest floor 35 70 5 25 Biomass on forest floor 5 5 5 5 Biomass below forest floor 60 25 90 70 Total 100 100 100 100

Based on the difference in the distribution of inorganic nutrients of the two forests, explain which forest will reestablish itself more quickly after logging. (3 marks)

(iii) Over-exploitation of forest resources leads to a decrease in biodiversity.

(1) Provide one reason why biodiversity is important. (1 mark) (2) Reforestation is a way to restore a forest. In earlier years, reforestation depended

mainly on exotic tree species imported from other countries and most of the plantations were formed by a single exotic tree species. State one criterion when choosing an appropriate exotic tree species for reforestation. Give one disadvantage of forming a plantation using a single tree species. (2 marks)


SECTION C Microorganisms and Humans Answer ALL parts of the question. 3. (a) Soy sauce is made by fermentation of a combination of soy beans, wheat grains, water and salt. The

production of soy sauce consists of three stages: incubating boiled soy beans and wheat grains with a fungus to produce the feedstock, fermenting the feedstock in the brine added, and pasteurising the raw soy sauce for bottling. An outline of the manufacturing process is given in the flow chart below:

Stage 3

Stage 2

Stage 1

Mixture of boiled soy beans and wheat grains

Filter the raw soy sauce and sterilise the filtrate by pasteurisation

Soy sauce ready for bottling

Add brine; inoculate with a salt-tolerant lactic acid bacteria and yeasts for further fermentation

Raw soy sauce: a mixture of lactic acid, amino acids, water, glucose and solid residue

Feedstock ready for fermentation

Inoculate with a fungus and incubate

(i) Explain why Stage 1 is an essential preparatory step for Stage 2. (2 marks)

(ii) Explain the importance of adding brine to the mixture in Stage 2. (2 marks) (iii) Why is it necessary to use pasteurisation in Stage 3 to sterilise the raw soy sauce? (2 marks)

(iv) Aseptic techniques are used in food manufacturing processes involving microbes. State the

principles of aseptic techniques. (3 marks)

PP-DSE-BIO 2–6 6

3. (b) The bacterium E. coli is a natural inhabitant of the human intestine.

(i) Figure 1 shows an E. coli infected by microbe M. Figure 2 is the magnified image of a part of Figure 1.

36000 28000

Microbe M

E. coli

Figure 1 Figure 2

(1) Identify microbe M. With reference to the above figures, state one observable difference between E. coli and microbe M. (2 marks)

(2) Describe briefly the events shown in Figure 2. (2 marks) (3) In the mass production of human insulin, E. coli is genetically modified to carry the

human insulin gene. Explain why bacteria (e.g. E. coli) are suitable for use in recombinant DNA technology. (2 marks)

(ii) E. coli is used as a water pollution indicating organism. A beach with an E. coli count exceeding

1600 per 100 cm3 seawater is graded ‘Very Poor’ by the Environmental Protection Department. A ‘Very Poor’ beach is not suitable for swimming. (1) Suggest why there is a health risk to people swimming in a ‘Very Poor’ beach. (1 mark)

(2) A student collects a water sample from a beach to determine its E. coli count. He filters

50 cm3 of the water sample through a membrane filter, on which bacteria are retained. The membrane filter is then placed on a nutrient agar plate suitable for the growth of E. coli and incubated for 24 hours. This step and the result after incubation are shown in the figure below:

Incubate for 24 hours

Membrane filter

Nutrient agar

(I) Explain how this method can be used to determine the E. coli count of the water sample. (2 marks)

(II) Calculate the E. coli count per 100 cm3 of the water sample. Based on your calculation, determine if this beach is ‘Very Poor’. (2 marks)


SECTION D Biotechnology Answer ALL parts of the question. 4. (a) Severe combined immune deficiency (SCID) is an inherited disease. One form of SCID is caused by a

gene mutation which renders the person unable to produce lymphocytes. Thus, people with this disease are susceptible to infections and, if untreated, rarely live past the age of two. To cure the disease, patients are transplanted with stem cells from the bone marrow of a healthy person. In 2000, it was first demonstrated that the disease could be cured by somatic gene therapy. In this therapy, a virus is used as a vector to incorporate the normal gene into the bone marrow cells of the patient.

(i) Why can transplanting bone marrow stem cells to SCID patients be used for treating the disease?

(1 mark)

(ii) What is the basis of using somatic gene therapy for treating SCID? Give one advantage of treating SCID patients with somatic gene therapy over transplanting normal bone marrow stem cells to the patients. (2 marks)

(iii) There is another type of gene therapy called ‘germ line gene therapy’. State two differences in

the biological consequences of using germ line gene therapy and using somatic gene therapy for treating SCID. (2 marks)

(iv) In 2002, three out of eleven SCID children who received this somatic gene therapy treatment got

leukemia (a type of blood cancer). Some scientists believe that the occurrence of the blood cancer is related to the incorporation of the normal gene into the bone marrow cells using a virus as the vector. Suggest an explanation for this belief. (2 marks)

PP-DSE-BIO 2–8 8

4. (b) Polymerase chain reaction (PCR) is a technique in modern biotechnology. A cycle of PCR consists of three principal steps, which operate at 95°C, 55°C and 72°C in sequence.

(i) Outline what happens in the three principal steps in a cycle of PCR. (3 marks)

(ii) One application of PCR is Polymerase Chain Reaction–Short Tandem Repeat Analysis

(PCR–STR analysis) which can be used in forensics. In a crime scene, a piece of hair suspected to be the criminal’s is found. A suspect is arrested one week later.

(1) With reference to the above case, state the significance of PCR in PCR–STR analysis.

(1 mark) (2) Describe how the products of PCR are used in PCR–STR analysis to produce evidence

for verifying whether the suspect has committed the crime. (3 marks)

(iii) Another application of PCR is for identifying GM organisms. The following shows the analysis of the DNA of a GM maize and a non-GM maize: [Note: The number above each peak in the figure indicates the number of base pairs (bp).]

Time (s)

GM-maize

Non GM-maize

5 15 25 35 45

25

50

75

100

125

150

175

101

151

151

DNA ladder

(1) A marker (a polynucleotide chain) with 101 bp is introduced to the maize in producing the GM maize. With reference to the above analysis, suggest the purpose of introducing a marker to the maize in the process of producing the GM maize.

(2 marks)

(2) Illustrate with an example how GM plants can help promote people’s health. (2 marks) (3) What are the possible impacts on the ecosystem of growing GM plants that produce a

toxin to kill insects? Describe two possible impacts. (2 marks)

END OF PAPER

Sources of materials used in this paper will be acknowledged in the Hong Kong Diploma of Secondary Education Examination Practice Papers published by the Hong Kong Examinations and Assessment Authority at a later stage.

PP-DSE-BIO 2–9 9

鳴謝 Acknowledgements

本專輯的試題曾引用下列刊物的資料： Material from the following publications has been used in question papers in this volume: Image: amphibian http://lh4.ggpht.com/_ox1kneyvfeU/Sx6yZCYVXMI/AAAAAAAAAT8/kcvREKop9SE/CRW_0604.jpg Image: amphibian http://www.basilbaker.com/Book_Review/Poison_Dart_Frog_from_French_Guiana.jpg Image: flower http://www.hiren.info/desktop-wallpapers/flowers-pictures/yellow-gerbera-daisy-5y Image: flower http://1.bp.blogspot.com/_xsW6PJwV7hc/S0vFfJ7DSvI/AAAAAAAAACU/Qt5y1c9PBQo/s320/wilted-flower1.jpg Image: small intestine http://www.bu.edu/histology/ Image: leaf section http://www.plantscienceimages.org.uk/images/fullsize/L16.jpg Image: cell http://library.thinkquest.org/3564/Cells/cell93.gif Image: rods & cones http://asset.nordicphotos.com/watermark/sciencephotorf/np03874103.jpg Image: E.coli http://www.washington.edu/alumni/partnerships/biology/200710/kerr.html Image: bacteriophage http://www.innophage.com/images/im1.jpg Image: agar plate http://web.mit.edu/watsan/images/Others/Laboratory/Lab-Fecal_MF_plate.jpg 專輯內試題引用的資料，蒙有關出版社╱機構准予使用，本局深表感銘。倘當中

引用的資料有未及取得版權持有者同意，或因未悉其來源而有牴觸版權之處，祈

為鑒諒。本局已盡一切努力追溯資料的來源，如有因資料來源錯漏而導致牴觸版權的情

況，懇請有關的版權持有者聯絡本局，以便作出適當的安排。 The Authority is grateful to publishers/organisations for permission to include in the question papers material from their publications. We apologise for any infringement of copyright in respect of material printed in this volume, for which permission has not been obtained in time or for which the sources could not be traced. Every effort has been made to trace copyright. However, in the event of any inadvertent infringement due to errors or omissions, copyright owners are invited to contact us so that we can come to a suitable arrangement.

http://lh4.ggpht.com/_ox1kneyvfeU/Sx6yZCYVXMI/AAAAAAAAAT8/kcvREKop9SE/CRW_0604.jpg

http://lh4.ggpht.com/_ox1kneyvfeU/Sx6yZCYVXMI/AAAAAAAAAT8/kcvREKop9SE/CRW_0604.jpg

http://1.bp.blogspot.com/_xsW6PJwV7hc/S0vFfJ7DSvI/AAAAAAAAACU/Qt5y1c9PBQo/s320/wilted-flower1.jpg

http://1.bp.blogspot.com/_xsW6PJwV7hc/S0vFfJ7DSvI/AAAAAAAAACU/Qt5y1c9PBQo/s320/wilted-flower1.jpg

http://asset.nordicphotos.com/watermark/sciencephotorf/np03874103.jpg

http://www.innophage.com/images/im1.jpg

http://web.mit.edu/watsan/images/Others/Laboratory/Lab-Fecal_MF_plate.jpg

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